GREENE: This is the sound from one of the many videos uploaded onto the Internet yesterday showing Syrian civilians, including children, convulsing and gasping for breath in an area outside of Damascus that's a rebel stronghold.

MONTAGNE: The symptoms of those victims seem consistent with injuries suffered in a chemical weapons attack. And that alleged attack earlier this week by the Syrian government prompted an emergency meeting last night at the U.N. Security Council which called for an investigation.

GREENE: The Syrian government has denied using any chemical weapons, though in the past American and other Western intelligence agencies concluded that the regime likely did use such weapons, though on a much smaller scale. Let's turn to talk to two people following these events closely. In a moment, a former weapons inspector, but first we go to Financial Times reporter Abigail Fielding-Smith in Beirut.

So are getting any more clarity at all about these potential chemical attacks and what exactly happened?

ABIGAIL FIELDING-SMITH: Yesterday morning, in the early hours of the morning, a major bombardment was launched on the Guta region, which is a kind of belt of farmland and towns surrounding Damascus. And activists say that part of that, some kind of poisonous gas was released. And over 100 videos were uploaded online, seeming to show people in a lot of distress without physical sort of obvious injuries or bleeding.

Nonetheless, they were struggling to breathe. In terms of the death toll and exactly where the attacks happened, I think there's still kind of quite a wide variety of narratives about that.

GREENE: The videos that you're talking about are coming from opposition groups. We don't have any independent confirmation yet, I mean from journalists or independent groups who have gone to these places.

FIELDING-SMITH: Well, I mean journalists and independent groups don't have the opportunity to go to this place, access to the city, let alone the rebellious suburbs - has been heavily, heavily restricted. There are a team of the U.N. inspectors in town, ironically, who are there to investigate three previous allegations of chemical weapons use, are getting to sort of extend their mandate to be able to investigate this.

It's not going to be straightforward at all. The U.N.'s mandate to be there and the sort of terms of inspections were the product of months of negotiations. Some people who have sort of allied to the regime have implied that this is something that has somehow been fabricated by the opposition to try and sort of focus attention while the U.N. is in town and could mobilize international opinion against the regime.

GREENE: Would the opposition be capable of fabricating something on a scale like this?

FIELDING-SMITH: I mean my gut reaction and the reaction of most of the analysts I've spoken to is that, I mean these videos(ph) - there's simply too many of them. And too many of them involve children who just - I don't see how they could be coached to act those kind of things. It just seems highly implausible that the entire kind of range of symptoms that we've seen and people in distress are some kind of, you know, movie film(ph) effect.

I mean I suppose what it is important to be kind of careful about is the scale of the deaths.

GREENE: And there have been some videos and reports of really crowded clinics in the area where this allegedly took place. What are we hearing about the medical conditions?

FIELDING-SMITH: That's right. I mean when you look at some of the videos, they appear to be in makeshift hospitals, and the scenes are really of kind of panic and overwhelmedness. There's, you know, people on the floor - there seems to be some kind of basic handheld kind of respirator pumps, but I mean it's not clear what people actually have to expunge this.

GREENE: One thing we should be clear about is these around Damascus, this belt of farmland you're talking about, has been bombarded by the government for some time. These are rebel areas.

FIELDING-SMITH: That's right. Basically the areas sort of surrounding Damascus have always been much more of a kind of stronghold of opposition sentiment. And then, you know, lately when it turned into a civil war, then they also became now an important base for armed groups. And the regime has been in this longer ongoing sort of effort to kind of crush them and push them back from the suburbs.

But I mean certainly if the upper estimates are right, this is the worst single incident we've seen in the whole two and a half year long crisis, certainly in terms of how it's going to play out and how it's making people feel, a kind of hardening attitude that's one of the worst things we've seen.

GREENE: We've been talking to Abigail Fielding-Smith with the Financial Times in Beirut. Abigail, thanks so much.